This species can be confused with other Amblyraja species with different distributions, such as Amblyraja georgiana (M. Stehmann pers. comm). In the northwest Atlantic, it is easily confused with Jensen' s skate (A. jenseni). Refer to Bigelow and Shroeder (1953), Jensen (1948) and Stehman and Burkel (1984).

Justification:
The Arctic Skate (Amblyraja hyperborea) is a widespread, deepwater skate found in the North Atlantic, southwest and East Pacific, and off southern Australia in the Eastern Indian Ocean, occurring from 260 to 2,500 m. These are primarily at depths greater than most fisheries along lower continental slopes and therefore this species has apparently limited interaction with human threats. There is also no current fishery interest, although it is an occasional bycatch.

The species reaches a maximum size of about 1 m total length (TL), and appears to live exclusively at temperatures below 4ºC. In the Northwest Atlantic, this species has been taken occasionally in research trawls and in deepwater commercial fisheries off Canada. It is commonly caught during surveys on the slope of the eastern Norwegian Sea and more recently in bottom trawl surveys of the Svalbard Archipelago. Given that this species is primarily distributed outside the reach of current fishing activity and has a wide geographic range, it is assessed as Least Concern. Continued monitoring of catches and expanding deepwater fisheries, and the collection of life history data should be a priority.

The Arctic Skate is widespread along lower continental slopes. In the Northeast Atlantic, this species is found from the Kara Sea, the southeast Barents Sea (Franz Josef Land and northern Novaya Zemliya Archipelagos), and the Spitsbergen/Svalbard Archipelago to the Greenland-Iceland-Faroe-Shetland Ridge and northern Norway (Paz 2003, Dolgov 2013). Any records of the Arctic Skate from the North Sea and eastern English Channelas reported by England, Wales, and Northern Ireland are likely the result of misidentification or incorrect use of species codes (ICES 2013). In the Northwest Atlantic, it occurs in Davis Strait between southwest Greenland and Canada. Recently a small number of records were reported as far south as the Grand Banks in Canadian waters, although some of these records may be confused with Jensen's Skate (A. jenseni). In the Southeast Atlantic, it is found along the southern tip of South Africa. In the Eastern Indian Ocean, it is found off southern Australia. In the Southwest Pacific, it occurs around New Zealand and in the Eastern Pacific it is found in Costa Rica, Panama, Colombia, and Ecuador.

No data on population size are available, however survey data indicate that this is the dominant skate species in certain areas, such as Davis Strait and southern Baffin Bay (Jørgensen 2005, 2011). The Arctic Skate was caught commonly during research cruises conducted on the slope of the eastern Norwegian Sea from 1984 to 1987 and in 1995 (Skjæraasen and Bergstad 2001). In the Spanish bottom trawl survey carried out on the Spitsbergen/Svalbard archipelago in 2003, it was also one of the main species caught (Paz 2003). Average annual catch rate between 1992 and 2005 was 0.6 individuals per square kilometer in the Barents Sea, which is considered ‘rare’ (Williams et al. 2008). Between 1996 and 2001 in the Barents Sea, the largest bycatch was 60-100 kilograms (kg) per hour haul, and more than 50 individuals per 1,000 hooks (Dolgov et al. 2005a). Average bycatch in the trawl fishery was 6-10 kilograms per hour haul and the maximum catch rate was 156 kg per hour. In the longline fishery, average bycatch rates were 10-25 individuals (or 35-75 kg) per 1,000 hooks, and catch rates reached 368 kg per 1,000 hooks (equivalent to a catch per vessel per day of approximately nine tonnes). These catch rates suggest that on average, this skate accounted for approximately 20% of longline catches, although they could comprise 99% of some catches. These catch rates suggest that it is a relatively common species in parts of the Northeast Atlantic. There are no data available on the population from other regions of occurrence.

The Arctic Skate is widespread in deep shelf waters and along continental slopes, and records range predominantly between 300 and 1,500 m, but reach depths of 2,500 m (Ebert and Stehmann 2013). This is an egg laying species, and size upon hatching is 16 to 18 cm total length (TL) (Bigelow and Schroeder 1953). Maximum size reported is 107 cm TL (Last and Stevens 2009); although the maximum recorded size in the Barents Sea is 74 cm TL (Dolgov 2011).

In Norwegian waters the highest frequency of catches observed were at depths between 1,050 to 1,250 m. In the deepest areas sampled (2,000 to 2,050 m) no catches were made, suggesting a lower limit to its depth range (Skjæraasen and Bergstad 2001). This species appears to live almost exclusively at temperatures below 4ºC (Bigelow and Schroeder 1953). In the Barents Sea, it prefers bottom temperatures about 0°C (Dolgov et al. 2005a).

This skate is taken as bycatch in deepwater trawl and longline fisheries. In Davis Strait, it is taken as bycatch in the Greenland Halibut (Reinhardtius hippoglossoides) fishery. In the Barents Sea it is taken in trawl fisheries targeting Cod (Gadus morhua) and Haddock (Melanogrammus aeglefinus) at depths of 300 m, and longline fisheries targeting mainly Greenland Halibut, Blue Catfish (Anarhichas denticulatus) and Cod at depths around 300 m (Dolgov et al. 2005b). These longline fisheries operate at depths of 130 to 847 m. Average bycatch rates in the longline fishery were 10 to 25 fish (or 35 to 75 kg) per 1,000 hooks, and this species was estimated to constitute approximately 20% of total longline catches (Dolgov et al. 2005b). However, it should be noted that the uncertainty of the estimates from this method is high (approximately ±45%). Preliminary estimates indicate that total annual skate bycatch in these fisheries is 723 to 1,891 tonnes, and the Thorny Skate (A. radiata) composes the great majority of catches (90 to 95% of the total skate catch). Skate catches are mainly discarded in the Barents Sea, although in 2000, about 200 tonnes of grouped Thorny and Arctic Skate were landed (Dolgov et al. 2005b), so future trends should be monitored. This skate is able to find refuge at depth as it primarily occurs outside the reach of fisheries.

In 1999, the European Union (EU) introduced a Total Allowable Catch (TAC) for skates and rays of 6,060 tonnes (t) for fisheries operating in the Norwegian Sea (International Council for the Exploration of the Sea [ICES] Division IIa) and North Sea (ICES sub-area IV) based on landing statistics from the previous five years. This TAC has been progressively reduced by 8−25% annually to the current level of 1,256 t. As part of the TAC, the bycatch quota for vessels over 15 meters was set at 25% of live weight of catch retained on board per trip. For much of this period (1999−2014), the TAC was higher than reported landings and therefore not effectively constraining catches.

Skate and ray TACs were established for other EU waters in 2009, including the Skagerrak and Kattegat (ICES Division IIIa) and from the northwest coast of Scotland and Northern Ireland to Portuguese waters (ICES sub-areas VI−IX). These TACs have also been gradually reduced since then. In 2013, the TAC for all skate and ray species grouped was 21,800 t (regulations are available online at http://faolex.fao.org).

Deepwater fisheries in the Northeast Atlantic have decreased in effort gradually over the past decade (Dransfeld et al. 2013, STECF 2014), but should still be monitored in case of future expansion, which could pose a threat to this skate.

Research to collect information on the biology, ecology, use, and fishery data of this species should be a priority.